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A panel of human monoclonal antibody Fab fragments has been generated against the surface glycoprotein gp120 of type 1 human immunodeficiency virus (HIV) by antigen selection from a random combinatorial library expressed on the surface of filamentous phage. The library was prepared from 5 ml of bone marrow from an asymptomatic individual who has been HIV-positive for 6 years. The antibodies have high affinity for antigen (mostly with affinity constants of greater than 10(8) M-1) and notable sequence diversity. Given appropriate donor selection, the methods described should allow the generation of antibodies for the evaluation of passive immunization as a therapy for AIDS.

A 27-nm particle was observed by immune electron microscopy in an infectious stool filtrate derived from an outbreak in Norwalk, Ohio, of acute infectious nonbacterial gastroenteritis. Both experimentally and naturally infected individuals developed serological evidence of infection; this along with other evidence suggested that the particle was the etiological agent of Norwalk gastroenteritis.

Infectious human respiratory syncytial virus (RSV) was produced by the intracellular coexpression of five plasmid-borne cDNAs. One cDNA encoded a complete positive-sense version of the RSV genome (corresponding to the replicative intermediate RNA or antigenome), and each of the other four encoded a separate RSV protein, namely, the major nucleocapsid N protein, the nucleocapsid P phosphoprotein, the major polymerase L protein, or the protein from the 5' proximal open reading frame of the M2 mRNA [M2(0RF1)]. RSV was not produced if any of the five plasmids was omitted. The requirement for the M2(0RF1) protein is consistent with its recent identification as a transcription elongation factor and contirms its importance for RSV gene expression. It should thus be possible to introduce defined changes into infectious RSV. This should be useful for basic studies of RSV molecular biology and pathogenesis; in addition, there are immediate applications to the development of live attenuated vaccine strains bearing predetermined defined attenuating mutations.Human respiratory syncytial virus (RSV) is the most important pediatric viral respiratory pathogen worldwide (1-3). This ubiquitous highly infectious agent emerges each year in seasonal epidemics and nearly everyone is infected at least once within the first 2 years of life. RSV disease is responsible for considerable morbidity and mortality and lacks an approved vaccine or highly effective antiviral therapy. Research on RSV is impeded by its poor growth in tissue culture, the instability of the virion, and the lack of a highly permissive experimental animal other than the chimpanzee.Resistance to RSV reinfection induced by natural infection is incomplete but increases incrementally with repeated exposure. Thus, RSV can infect multiple times during childhood and later life, but serious disease usually is limited to the first and sometimes second infections of life. The minimum goal of RSV immunoprophylaxis is to induce sufficient resistance to prevent serious disease associated with the first or second infection.RSV is a member of the pneumovirus genus of the paramyxovirus family (1, 4 The development of methods for introducing designed changes into genomic RNA of nonsegmented negative-strand RNA viruses was impeded by the lack of homologous viral recombination and the lack of infectivity of naked genomic RNA. The supposition that the minimum unit of infectivity for this type of virus is a nucleocapsid competent for RNA synthesis suggested a different strategy to produce infectious virus from viral cDNA. This involved the intracellular coexpression, from separate transfected plasmids, of cDNAencoded genomic or antigenomic RNA and those viral proteins necessary to generate a transcribing and replicating nucleocapsid. cDNA expression would be driven by T7 RNA polymerase supplied by a vaccinia recombinant virus. This approach was developed first by using short internally deleted analogs of genomic or antigenomic RNA ("minigenomes") that were shown to participate in...

Abstract. The recombinant dengue virus type-4 vaccine candidate 2A⌬30 was attenuated in rhesus monkeys due to an engineered 30-nucleotide deletion in the 3Ј-untranslated region of the viral genome. A clinical trial to evaluate the safety and immunogenicity of a single dose of 2A⌬30 was conducted with 20 adult human volunteers. The vaccine candidate was well tolerated and did not cause systemic illness in any of the 20 volunteers. Viremia was detectable in 14 volunteers at a mean level of 1.6 log 10 plaque-forming units/ml of serum, although all 20 volunteers seroconverted with a seven-fold or greater increase in serum neutralizing antibody titer on day 28 post-vaccination (mean titer ϭ 1:580). A mild, asymptomatic, macular rash developed in 10 volunteers, and a transient elevation in the serum level of alanine aminotransferase was noted in five volunteers. The low level of reactogenicity and high degree of immunogenicity of this vaccine candidate warrant its further evaluation and its use to create chimeric vaccine viruses expressing the structural genes of dengue virus types 1, 2, and 3.

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